Advanced Materials Research Vols. 512-515

Abstract: CaF₂ is used in large quantity during refining of steel, which is harmful to environment to be found. There is more and more study on use of B₂O₃ in metallurgical progress. This paper studied the effects of MgO on melting performance of CaO-SiO₂-Al₂O₃ ternary system and B₂O₃ on that of CaO-SiO₂-Al₂O₃-MgO quaternary system by calculation of phase diagram. The result shows that MgO can expand the range of liquid phase of CaO-SiO₂-Al₂O₃ ternary system while the effect on melting performance is little. B₂O₃ can also reduce the melting point of CaO-SiO₂-Al₂O₃-MgO quaternary system in high CaO zone and in high Al₂O₃ zone. So the proper composition of MgO in refining slag are 5~8% and B₂O₃ below 8%.

Abstract: Carbon coated N-doping of TiO₂ nanotube films were successfully prepared by a two-step process of anodization and gas thermal penetration. The morphologies and structures of composites were characterized by SEM, XRD, XPS and Raman spectroscopy analyses, respectively. The results show that graphitized carbon deposited on the surface of TiO₂NTs nanotubes under gas thermal penetration conditions, by which N atoms are incorporated into the lattice of TiO₂NTs through substituting the site of oxygen atoms. Such Carbon coated N-doping of TiO₂ nanotube films presents the enhance absorption in visible region. The photo catalytic tests show that the prepared films at 600°C reveal higher photocatalytic activity for splitting of water than other samples.

Abstract: At the beginning of the new century, China’s economic growth accelerated. The demand of coal as a basic energy is keeping increase [1]. With the progress of the mining technology, changed the past low efficiency, backward mode of production, but there are still many adverse factors that restrict to the sustainable development of coal industry in China [2]. Through detailed analysis of the current situation of China coal industry, find out existing problems of Chinese coal industry sustainable development, and using the basic principle [3], to find suitable to Chinese coal industry sustainable development scientific proposition -- Circular Economy [4], using circular economy this scientific model to guide Chinese coal enterprises transformation and development, making Chinese coal enterprises realize sustainable development.

Abstract: In this paper, a facile hydrothermal method has been developed for preparation of micro/nano structures of ZnS microspheres and ZnO microrods. The morphologies and crystalline structures were confirmed by scanning electron microscopy (SEM) and X-ray diffraction spectrum (XRD). In the co-existence of cysteine and hexamethylenetetramine (HMTA), we observed the competitive growth of ZnS and ZnO microstructures, and found that higher temperature was benefited for the formation of ZnS structures. This method may be applied for synthesis of other metal compound micro-nano structures with other metal ions. ZnS and ZnO semiconductor nanostructures as often-used photo-catalyst, we also compared their catalytical activity toward to the photo-degradation of methylene blue.

Abstract: Using first-principles density-functional theory investigate (5, 5) capped single-walled carbon nanotubes adsorbed at one end by hydrogen molecule with and without an applied electric field. It is found that the structure of carbon nanotubes with hydrogen molecules is stable under field-emission conditions. The induced dipole moments is the direction of the applied electric field，and the LUMO-HOMO energy gaps decrease. These results elucidate that the field-emission properties of carbon nanotubes can be enhanced by the adsorption of hydrogen molecules, and are consistent with the experimental results.

Abstract: Clean coal briquette is one of the most effective techniques to remove SO₂ from coal combustion by using sulfur-retention agent to retain sulfur in coal residuals. Ca(OH)₂ has been proved to be an effective sulfur-retention agent. CaSO₄ as the primary sulfur-containing product, however, is thermal unstable at high temperatures. It has been reported that SiO₂, Al₂O₃, Fe₂O₃ etc. are excellent sulfur retention additives, those are abundant in coal fly ash. In this study coal fly ash was used to the additive to improve the sulfur retention of coal briquette. The results showed that the addition of coal fly ash can improve the sulfur retention. The modified coal fly ash obtained by calcinations assisted with Ca(OH)₂ can improve the sulfur retention more noticeable. The SEM and XRD results further indicated that coal fly ash promoted the formation of the sulfur-containing products such as Ca-Si-S-O compounds with high thermally stability.

Abstract: Direct magnetic field was imposed during the process of rapid quenching by melt spinning of MlNi_3.6Co_0.7Mn_0.4Al_0.3 and MlNi_3.6Co_0.35Mn_0.5Al_0.3Cu_0.25. The effect of rapid quenching in magnetic field on the microstructures and electrochemical performances was investigated in detail. The results show that rapid quenching decreases the grain size of both alloys, and magnetic field results in an oriented growth especially for MlNi_3.6Co_0.35Mn_0.5Al_0.3Cu_0.25 alloys, but they have little influence on the typical CaCu₅ structure of AB₅-type alloys except for the increase of cell parameters (a₀, c₀) and cell volume. Electrochemical studies indicate that rapid quenching enhances the cycle stability significantly but inevitably decreases the electrochemical capacities of the alloys unless magnetic field was imposed. Additionally, the diffusion of hydrogen and rate properties are improved with the emergence of magnetic field compared with the alloys processed by rapid quenching only.

Abstract: Sol-gel thin films prepared by dipping coating technique, sol–gel derived bulk were prepared from constant water (H₂O)/tetraethyl-orthosilicate (TEOS) ratio, dipping coating were carried out at different dipping speed 100mm/min, 200mm/min, 300mm/min, 400mm/min, 500mm/min respectively. The films are characterized by ellipsometer and SEM respectively. The experimental results show the thickness of films are become bigger and bigger with the dipping speed increasing.The refractive index change is not obvious.

Abstract: Supported rare earth double perovskite (La2MnNiO6) oxide catalysts were prepared by incipient wet impregnation method for methane catalytic combustion, and effects of the support (Al₂O₃, ZrO₂ and MgO) were investigated. The loaded catalysts were characterized by means of XRD, TPR, SEM techniques and their catalytic activities were tested by complete methane oxidation. Depending on the different oxide carrier (e.g. Al₂O₃, MgO and ZrO₂), catalysts have different catalytic properties, because the interaction of metal oxide-support will affect both redox property and dispersity of the active phase. The results on catalysts have shown that the dispersion on Al₂O₃ and MgO supports had an effect to enhance the catalytic performances of the catalysts that had been treated at 1100 oC. The activity of ZrO₂ supported catalyst significantly decreases when calcination temperature at is 1100 oC. The dispersity of the active phase and the nature of the oxide carrier played an important role in the catalytic performance.

Abstract: Economizers are widely employed in the boiler system to increase efficiency and save energy. However one prominent problem is the severe corrosion of economizer due to the decrease of the exhaust temperature of boiler. Ni–P/Cu/Ni-P multilayer coatings, which could effectively improve the corrosion resistance of the facilities in economizer, are introduced in the present work. The three-layer coatings, whose composition is Ni–P/Cu/Ni-P from substrate to surface, were prepared using dual baths (acidic hypophosphite-reduced electroless nickel bath and acidic replacement electroless copper bath). The corrosion resistance of the coatings was evaluated by porosity and electrochemical tests. The results of porosity evaluation show that all the multilayer coatings performed better than the single-layer coatings of similar thickness. Similarly, The electrochemical tests showed lower corrosion current density for the multilayer coatings in 3.5 wt.% NaCl aqueous solutions.